Dead-simple nested timers for Ruby

nested_timers.rb

class MyTimerClass
  attr_reader :timers

  def initialize
    @timers = {}
    @parent_timer = nil
  end

  def clock!(name, &block)
    @timers[name] ||= 0
    parent_timer = @parent_timer
    @parent_timer = name
    start_time = Time.now

    result = yield block

    diff_time = Time.now - start_time
    @timers[name] += diff_time
    @timers[parent_timer] -= diff_time if parent_timer
    @parent_timer = parent_timer

    result
  end
end

$timer = MyTimerClass.new

$timer.clock! :main do
  10.times do
    $timer.clock! :sleeping do
      sleep rand
    end

    $timer.clock! :eating do
      print "om "
    end

    $timer.clock! :eating do
      print "nom "
    end
  end
  print "\n"
end

p $timer.timers